[Mailman-Users] moderator page behind nginx with SSL

The rest of mailman version 2.1.22 is working fine with SSL and some rewriting by nginx and yet https://cibolo.us/mailman/admindb/open_electroporator gives a message "will be sent over an insecure connection" when I seta button to discard and then do the submit all data button.

Is there a way to use SSL here?

Or... will I need to disable SSL for this page to get that submit to work?